Process of lithography.



TUNE @TATE PATENT FFIQE,

SAMUEL A. NEIDICH, OF EDGEWATER PARK, NEW JERSEY, ASSIGNOR T0 THE AMERI- CAN MULTIGRAPH COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO. I

PROCESS OF LITHOGRAPHY.

To all whom t may concern.'

Be it known that I, SAMUEL A. NEiDiCH, a citizen of the United States, residing at Edgewater Park, in the county of Burlington and State of New Jersey, have invented a certain new and useful Improvement in Processes of Lithography, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

This invention relates to a process for the preparation of a metal lithographie plate, the object being to reduce the expense, time and skill required in the preparation of a plate for printing, as Well as to produce a more durable plate and one having other desirable properties hereinafter mentioned. In the ordinary process of preparing metal lithographie plates, a grained plate has the work or image applied direct to it in some greasy medium and thereafter the balance of the plate is etched and gummed to make it ink-resisting when moist.

In the old processes it is very important that no grease be present on the grained plate where printing is not desired, and that the plate be kept free from oxidization, and great skill is required as well as considerable time in accomplishing the etching. Inasmuch as the etching operation tends to remove tlie work, the usual method has been to partially etch the plate and thereafter strengthen the work and then further etch the plate and further strengthen the work, if necessary. 'Ihese successive operations require great skill and caution, lest the Work be partially removed by the etching substances. 'Ihere is great liability of spoiling the plate during this process, for if the etching removes the least part of the work, the

plate is ruined, or is only preserved by tedious subsequent operations. Unless the operation is carried out with the greatest possible care, the plate lacks durability, as the image is liable to become partiallyremoved during the operation of the printing. Furthermore, the work as ordinarily prepared upon the plate is soluble in all .the ordinary solvents for ink, and should ink accidentally be permitted 'to dry on the face of the plate, it is difficult of removal without also removing the work.

In my process I take a grained plate, etch its entire face before applying any work and Specification of Letters Patent.

Application i'led August 11, 1914.

Patented Oct. SO, im "32. serial no. 856,202.

thereafter I apply the Work directly to the etched surface, the substance of the work or image being of such character that it will adhere to the etched surface so firmly as to be practically impossible of removal, while having the ability to receive ink.l By this process I do away with the element of skill in the etching operation, as I am not hampered by the presence of any work on the plate. I very materially shorten the time required, since I can use the strongest etching solution and accomplish it at one time instead of by several successive operations. The plate is not liable to be spoiled by reason of ink inadvertently drying on the surface, for at any time such ink may be dissolved oif without affecting the work. Finally, my plate is more permanent both in itsink-carrying and ink-resisting properties.

Inasmuch as the etching of my plate is entirely independent of the character of the work to be produced, it is possible to perform the etching as a manufacturing operation, in conjunction with the graining of the plate, and to supply to users ready-etched plates having wonderfully greater keeping qualities than the usual grained plates, as well as free from the possibility of damage from accidental grease deposits or from oXidiZation. Chemical manipulation of the plate-by the user-is thereupon eliminated as he is only required to apply the image to the plate by means of a suitable liquid compound and secure it by heating, as will be hereinafter more fully described.

Describing my process more particularly, I take a plate of Zinc, aluminum or other suitable metal, grained as in the ordinary lithographic process, and I etch the entire face' thereof very completely, so -as to make a thoroughly ink-resisting surface. For this purpose I may use any of the well-known etching compounds, but I prefer to use the strongest of such compounds, as now employed for the last step of etching with work on the plate. My etching operation preferably includes the gumming ofthe plate with the ordinary gum arabic solution, after which the plate is dried. The grained, etched and' gummed plate may be delivered to the customer for use and may be kept in stock indefinitely, although I prefer to incorporate in the gum an einulsified hard wax, as simplifying' the operation by the user. rll`his may be conveniently accomplished by mixing with the usual gum arabic solution an emulsion of carnauba with water so that the final mixture will contain approximately equal quantities of solid gum arabic and solid carnauba wax, the latter in suspension. rthe emulsilied carnauba may be obtained on the market oremulsilcation may be accomplished in any well known manner, as for example, by employing amid duron or stearamid (i. e., the amid of stearic acid, CHHSCONHZ) which is on the market for such purposes. Y

In applying the work to the plate, use a solution adapted to render the gum insoluble in water, which combines with the wax and gum, when heated. to form a hard, resistant, firmly-attached substance which readily receives ink. Various substances may be used for this work solution. have obtained very satisfactory results by applying a ten per cent. solution of bichroinate of ammonium locally where the image is so formed.

After the solution described is applied to the plate, it is only necessary to heat the plate for a few seconds at a temperature approximately 200O Fahrenheit, thus melting the carnauba wax and driving oft' the water and forming on the plate an insoluble dry compound of wax and bichromated gum, the reaction between the three materials being practically instantaneous and easily determined by the blackening of the image. Such plate is then ready for use in printing and may be employed for an indefinite time in the ordinary lithographie process. My tests have demonstrated that the plate is practically indestructible and that the work is insoluble in all of the ordinary ink solvents.

lilith equal ease, the emulsion may be omitted from the gum covering the entire plate and applied locally in admixture with the bichromate solution. Various modifications may be made in this process, provided the essential feature is retained of forming on a pretched plate, where the image is desired, a compound which attaches firmly to the plate and which will take ink.

lt should be noted by way of distinction, that in my process the bichromate of ammonium is used without reference to its photographic quality, and the applying and heating may be accomplished with or without the action of light.

Any of the known equivalents may be employed for the bichromate of ammonium, and other waxes or grcases may be substitited for the carnauba wax, carnauba being preferred on account of its exceptional hardness and insolubility in ordinary solvents.

ll desire to emphasize the fact that the inkreceptive material It employ for the Work has paraiso characteristics enabling it to firmly adhere to the surface which has been etched to such an extent that, when moist, it. is so ink-repellent that no subsequent chemical treatnient of the plate is necessary after the work is applied. The avoidance of chemical operation after the work has been applied relieves the user of a very troublesome feature which has existed in prior methods. ln my process the chemical treatment is effected by the manufacturer, and the user has simply to apply the image and atlix it by heat.

My processl is further illustrated in the drawings attached hereto, in which Figure 1 is a cross section very much enlarged, of an KVordinary grained metal plate; Fig. 2 is a cross section of such plate after the entire face thereof has been etched; Fig. 3 is a cross section after the gumming of the etched plate: Fig. Je is a cross section after the work is applied, and Fig. 5 is a plan of a portion of the plate shownin Fig. '-l.

In Figs. 1 to l, A represents the body of the metal plate and a the grained surface thereof; B represents the coating formed by the action ofY the etching materials on the zinc, Vwhich is a substance capable, when moist, of rejecting ink. This etching is shown graphically as higher than the grain, though in reality it is incorporated with it. C (Fig. 3) indicates the coat of gum arabic over the etched plate, holding in suspension microscopically minute particles of hard wax deposited therein by the drying of an emulsion of such wax in the gum solution. rThese particles are indi lated by the dots D. rthe coating (l differs from the coating B in that the former may be removed by water, whereas the etched coating cannot. E in Figs. JC and 5, indicates the image which is applied to the plate shown in Fig. 3. T he substance of this image as described, is a hard resisting material which by heating becomes homogeneous and firmly attached to the etched plate.

In the above description it is to be understood that the word etch is used in the commonly accepted lithographie meaning of the word, to cover any means of making the surface ink resisting when moist, and not in the ordinary sense of the. word as meaning cuttino away of the metal by an acid. rThe wor work is used throughout to mean the image, which is to receive the ink and be duplicated in the printing process.

The process described refers more particularly to work consisting of autographic work, line drawings, artists sketches and other work in line effect, for reproduction on an off-set press, though my pretehed plate is adapted to receive work by other methods, one of which is covered in my copending application No. 856,201, tiled August 11, 1914. The pretehed plate itself,

ready to receive Work, forms the subject matter of my Patent No. 1,203,770, issued November 7, 1916.

Having thus described my invention, What I claim is:

1. The process of preparing a lithographic plate, consisting of etching a plate and drying on the etched surface a mixture of gum arabic and emulsiied hard Wax.

2. The process of preparing a lithographic plate, consisting of etching a previously grained plate and drying on the etched surface a mixture of gum arabic and emulsiied hard Wax, and thereafter applying the Work.

3. The process of preparing a metallic lithographic plate, consisting of etching and gumming a grained plate and thereafter applying to the etched surface the design in the form of a solution adapted after the application -of heat to adhere to the preetched plate and have the capacity for receiving ink.

-l. The process of preparing a lithographic plate, by etching the entire face of the grained plate, depositing thereon over lthe entire surface gum and hard Wax in suspension in the gum, and applying the Work by means of a solution of bichromate of ammonium or other agent Which renders the gum insoluble in the presence of heat.

The process of preparing a lithographic plate consisting of etching and gumming the entire face. of the plate, applying where the image is desired a solution of bichromate of ammonium or its equivalent in conjunction with an emulsiication of carnauba Wax.

6. The preparation of a lithographic plate comprising treating the entire face of the plate to make it ink-repellent and moisture attractive and forming the design over the. etched surface by means of a mixture of bichromate of ammonium and carnauba Wax.

7. The preparation of a lithographic plate comprising etching and gumming the entire face of the plate and forming the design over the etched surface by means of a mixture of bichromate of ammonium and carnauba Wax, and thereafter heating the plate with the design applied.

8. The process of preparing a metallic lithographic plate consisting of etching and gumming the entire face of the plate, applying the Work to the etched plate by means of a compound which when heated Will attach in the etched surface, and heating the plate and Work after the Work is applied. 9. The process of preparing a lithographic plate consisting of treating the plate to make it ink repellent and aliixing on the treated surface an image made by a Wax and a solution which is adapted to combine With the Wax to form a substance capable of receiving ink.

In testimony whereof, I hereunto affix my signature in the presence of tWo Witnesses. SAMUEL A. NEIDICH. lVitnesses:

ALBERT I-I. BATES, JUSTIN W. MAoKmN. 

